Method of forming a drum type washing machine having a driving unit

ABSTRACT

The washing machine includes a tub mounted in a cabinet, a drum mounted in the tub, a shaft that transmits a driving force from a motor to the drum, front and rear bearings mounted on an outer circumference of opposite end portions of the shaft, a bearing housing built in a central portion of a rear wall of the tub to support the front bearing, a rotor coupled to the rear end portion of the shaft, a stator fixed to the tub rear wall inward of the rotor, and a connector of the rotor that serration coupled to the outer circumference of the shaft in front of the rear bearing so as to transmit rotating power from the rotor to the shaft. A bearing bracket may be fixed to the rear wall of the tub so as to cover an outside of the rotor and support the rear bearing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of prior U.S. patentapplication Ser. No. 11/453,037 filed Jun. 15, 2006, which is aContinuation of U.S. patent application Ser. No. 10/669,445 filed Sep.15, 2003 (now U.S. Pat. No. 7,131,178), which is a ContinuationApplication of U.S. patent application Ser. No. 10/231,314 filed Aug.30, 2002 (now U.S. Pat. No. 7,114,355), which is a ContinuationApplication of U.S. patent application Ser. No. 09/624,144 filed Jul.21, 2000 (now U.S. Pat. No. 6,460,382), which claims priority under 35U.S.C. §119 to Korean Application Nos. 10-1999-0045088 and10-1999-0045089 both filed on Oct. 18, 1999, whose entire disclosuresare hereby incorporated by reference.

BACKGROUND

1. Field

The present invention relates to a drum type washing machine, and moreparticularly, to a structure of a driving unit in a drum type washingmachine.

2. Background

In general, a drum type washing machine washes using friction between adrum rotated by a motor and laundry, detergent, and washing water,introduced into the drum, and provides effects of beating and rubbingwhile doing almost no damage to the laundry, and causing no entanglingof the laundry. A structure of a related art drum washing machine willbe explained with reference to FIG. 1. FIG. 1 illustrates a longitudinalsection of a related art drum type washing machine, provided with a tub2 mounted inside of a cabinet 1, a drum 3 rotatably mounted on a centralportion of inside of the tub 2. There is a motor 5 a under the tub 2connected with a pulley 18. There is a drum shaft 4 connected to a rearof the drum 3, to which a drum pulley 19 is coupled. And, the drumpulley 19 on the drum shaft 4 and the motor pulley 18 connected to themotor 5 a are connected by a belt 20 for transmission of power. And,there is a door 21 in a front part of the cabinet 1, with a gasket 22between the door 21 and the tub 2. There is a hanging spring 23 betweenan inside of an upper portion of the cabinet 1 and an outside of anupper portion of the tub 2, and a friction damper 24 between an insideof a lower portion of the cabinet 1 and a lower side of an outside ofthe tub 2 for damping vibration of the tub 2 generated during spinning.

However, the related art washing machine has the following disadvantagessince driving power of the motor 5 a is transmitted to the drum 3through the motor pulley 18, and the drum pulley 19, and the belt 20connecting the motor pulley 18 and the drum pulley 19.

First, there is a loss of energy in the course of transmitting drivingpower because the driving power is transmitted from the motor 5 a to thedrum 3, not directly, but through the belt 20 wound around the motorpulley 18 and the drum pulley 19.

And, the transmission of driving power from the motor 5 a to the drum 3,not directly, but through many components, such as the belt 20, themotor pulley 18, and the drum pulley 19, causes much noise in the courseof power transmission.

The numerous components required for transmission of driving power fromthe motor 5 a to the drum 3, such as the motor pulley 18, the drumpulley 19 and the belt 20, require many assembly man-hours. And, themore the number of components required for transmission of driving powerfrom the motor 5 a to the drum 3, the more number of spots which requirerepair, and the more frequent at which repair required.

In summary, the indirect driving power transmission from the motor 5 ato the drum 3 through the motor pulley, the drum pulley, and the beltrequires many repairs, generates much noise, wastes energy, and resultsin a deterioration of a washing capability.

Moreover, the tub 2 of stainless steel in general in the related artdrum washing machine is expensive, has poor formability, and is heavy.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a structure of adriving unit in a drum type washing machine that substantially obviatesone or more of the problems due to limitations and disadvantages of therelated art.

An object of the present invention is to provide a structure of drivingunit in a drum type washing machine, which can reduce noise, repair andwaste of energy, and moreover, improve washing capability.

Another object of the present invention is to provide a structure ofdriving unit in a drum type washing machine, which has an improvedsupporting force.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, thestructure of a driving unit in a drum type washing machine having a tubmounted in a cabinet, a drum mounted in the tub, a shaft fixed to thedrum for transmission of driving power from the motor to the drum, andbearings mounted on an outer circumference of the shaft at opposite endportions thereof, includes a metallic bearing housing at a centralportion of a rear wall of the tub for supporting the bearings mounted onthe outer circumferences of opposite end portions of the shaft.

In other aspect of the present invention, there is provided a structureof driving unit in a drum type washing machine including a tub mountedinside of a cabinet, a bearing housing built in a central portion of arear wall of the tub for supporting a bearing therein, a shaft connectedto a drum mounted inside of the tub for transmission of a driving forcefrom a motor to the drum, bearings mounted on an outer circumference ofthe shaft at opposite end portions thereof respectively, a rotor coupledto a rear end of the shaft, a stator provided inward of the rotor fixedto the tub rear wall, a connector provided between the shaft and therotor for transmission of a rotating force from the rotor to the shaftfor rotating the shaft and the rotor together, and a supporter fittedbetween the rear wall of the tub and the stator for supporting thestator and maintaining a concentricity when the stator is mounted to thetub rear wall.

In another aspect of the present invention, there is provided astructure of driving unit in a drum type washing machine including a tubof plastic mounted inside of a cabinet, a metallic bearing housinginserted and built in a central portion of a rear wall of the tub havingsteps of “┐” and “└” forms on an inner circumference for supportingbearings therein, a shaft connected to a drum mounted inside of the tubfor transmission of a driving power from a motor to the drum, having afront end portion fixed to a spider in the drum rear wall, a brassbushing press fit on a region of the shaft from a portion exposed inrear of the spider to the front bearing for prevention of rusting of theshaft, and steps on an outer circumference thereof for fixing mountingpositions of the front bearing and the rear bearing on the shaft,bearings mounted on the outer circumference of the shaft at opposite endportions thereof respectively, a rotor of steel or steel alloy platecoupled to the rear end portion of the shaft, including a bent portionformed along a circumference thereof having a setting surface forsupporting magnets fitted to an inside of a front portion of a sidewallextended forward from a periphery of a rear wall, and a hub at a centerof the rear wall having a through hole for a fastening member, such as abolt, for coupling the rotor to the shaft, a plurality of cooling finsformed around the hub in a radial direction each with a length forblowing air toward the stator when the rotor is rotated for cooling downa heat generated at the stator, an embossing between adjacent coolingfins on the rear wall of the rotor for reinforcing the rotor, and adrain hole in each of the embossings, for drain of water, a statorcomposing the motor together with the rotor, fixed to the tub rear wallinward of the rotor, a connector of plastic provided between the shaftand the rotor for transmission of a rotating force from the rotor to theshaft for rotating the shaft and the rotor together, and a supporterfitted between the rear wall of the tub and the stator for supportingthe stator and maintaining a concentricity when the stator is mounted tothe tub rear wall.

In further aspect of the present invention, there is provided astructure of driving unit in a drum type washing machine including a tubmounted inside of a cabinet, a drum mounted inside of the tub, a shaftconnected to the drum mounted inside of the tub for transmission of adriving force from a motor to the drum, a front bearing and a rearbearing mounted on an outer circumference of the shaft at opposite endportions thereof respectively, a bearing housing built in a centralportion of a rear wall of the tub for supporting the front bearing, arotor composing the motor together with the rotor, and coupled to therear end portion of the shaft, a stator fixed to the tub rear wallinward of the rotor to compose the motor together with the rotor, aconnector serration coupled to the outer circumference of the shaft infront of the rear bearing and fixed to the rotor, for transmission of arotating power from the rotor to the shaft, and a bearing bracket fixedto the rear wall of the tub to cover an outside of the rotor and supportthe rear bearing.

In a still further aspect of the present invention, there is provided astructure of driving unit in a drum type washing machine including a tubof plastic mounted inside of a cabinet, a metallic bearing housinginserted to built in a central portion of a rear wall of the tub havingsteps on an inner circumference for supporting bearings therein, a shaftconnected to a drum mounted inside of the tub for transmission of adriving power from a motor to the drum, having a front end portion fixedto a spider in the drum rear wall, and a brass bushing press fit on aregion of the shaft from a portion exposed in rear of the spider to thefront bearing for prevention of rusting of the shaft, bearings mountedon the outer circumference of the shaft at opposite end portions thereofrespectively, a rotor of steel or steel alloy plate coupled to the rearend portion of the shaft, including a bent portion formed along acircumference thereof having a setting surface for supporting magnetsfitted to an inside of a front portion of a sidewall extended forwardfrom a periphery of a rear wall, and a hub at a center of the rear wallhaving a through hole for a fastening member, such as a bolt, forcoupling the rotor to the shaft, a plurality of cooling fins formedaround the hub in a radial direction each with a length for blowing airtoward the stator when the rotor is rotated for cooling down a heatgenerated at the stator, an embossing between adjacent cooling fins onthe rear wall of the rotor for reinforcing the rotor, and a drain holein each of the embossings, for drain of water, a stator composing themotor together with the rotor, fixed to the tub rear wall inward of therotor, a connector of plastic provided between the shaft and the rotorfor transmission of a rotating force from the rotor to the shaft forrotating the shaft and the rotor together, a supporter fitted betweenthe rear wall of the tub and the stator for supporting the stator andmaintaining a concentricity when the stator is mounted to the tub rearwall, and a bearing bracket fixed to the rear wall of the tub to coveran outside of the rotor and support the rear bearing.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention:

In the drawings:

FIG. 1 illustrates a longitudinal section of a related art drum typewashing machine;

FIG. 2A illustrates a longitudinal section of a drum type washingmachine in accordance with a first preferred embodiment of the presentinvention;

FIG. 2B illustrates a detailed enlarged view of “A” part in FIG. 2A;

FIG. 3 illustrates a perspective view with a partial cut away view ofthe rotor in FIG. 2;

FIG. 4 illustrates an enlarged perspective view of “B” part in FIG. 3;

FIG. 5 illustrates a perspective view of a bottom in FIG. 3;

FIG. 6 illustrates a perspective view of the stator in FIG. 2;

FIG. 7 illustrates a perspective view of the connector in FIG. 2;

FIG. 8 illustrates a perspective view of a bottom in FIG. 7; and,

FIG. 9 illustrates a longitudinal section of a driving unit in a drumtype washing machine in accordance with a second preferred embodiment ofthe present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. A first preferred embodiment of the present invention will beexplained in detail with reference to FIGS. 2A˜8. FIG. 2A illustrates alongitudinal section of a drum type washing machine in accordance with afirst preferred embodiment of the present invention, FIG. 2B illustratesa detailed enlarged view of “A” part in FIG. 2A, FIG. 3 illustrates aperspective view with a partial cut away view of the rotor in FIG. 2,FIG. 4 illustrates an enlarged perspective view of “B” part in FIG. 3,FIG. 5 illustrates a perspective view of a bottom in FIG. 3, FIG. 6illustrates a perspective view of the stator in FIG. 2, FIG. 7illustrates a perspective view of the connector in FIG. 2, and FIG. 8illustrates a perspective view of a bottom in FIG. 7.

The drum type washing machine in accordance with a first preferredembodiment of the present invention includes a tub 2 of plastic mountedinside of the cabinet 1, a drum 3 mounted in the tub 2, a shaft 4 fixedto the drum 3 for transmission of driving power from a motor 5 to thedrum 3, bearings 6 a and 6 b fitted on outer circumference of the shaft4 at both ends thereof, and bearing housings 7 of metal fitted tosupport the bearings 6 a and 6 b at a central portion of a rear wall 200of the tub 2. The bearing housing 7 of metal is formed as a unit withthe tub rear wall 200 by an inserted injection molding in the injectionmolding of the tub 2 of plastic. The bearing housing 7 is preferablyformed of aluminum. The bearing housing 7 has steps 8 a and 8 b forholding the front bearing 6 a and the rear bearing 6 b fitted in innercircumferences of the bearing housing 7 for preventing the bearings 6 aand 6 b from being separated therefrom. Of the steps 8 a and 8 b formedon the inner circumferences of the bearing housing 7, the front step 8 ahas a form of “┐” for supporting a rear end portion of the front bearing6 a fitted to a front end of an outer circumference of the shaft 4, andthe rear step 8 b has a form of “└” for supporting a front end portionof the rear bearing 6 b fitted to a rear end portion of the shaft 4.And, there are positioning steps 400 a and 400 b on outer circumferencesof the shaft 4 disposed inside of the bearing housing 7 which transmitsdriving power from the motor 5 to the drum 3, for fixing mountingpositions of the front bearing 6 a and the rear bearing 6 b on the shaft4. A front end of the shaft 4 is coupled to a spider 10 in a rear wallof the drum 3, a region of the shaft 4 that extends from a portionthereof exposed at a rear of the spider 10 to the front bearing 6 a hasa bushing 11 of brass press fit thereon for prevention of rusting, andthere is a sealing member 12 on an outer surface of the bushing 11 forpreventing ingress of water toward the bearing housing 7. There is arotor 13 of a direct coupling type motor 5 fixed to a center of a rearend of the shaft 4, and a stator 14 having a crown form fixed to therear wall 200 inside of the rotor 13. The rotor 13 and the stator 14together form the direct coupling type motor 5.

Referring to FIGS. 3˜5, the rotor 13 of steel or steel alloy plateincludes a bent portion formed along a circumference thereof having asetting surface 130 for supporting magnets 13 c fitted to an inside offront of a sidewall 13 b extended forward from a periphery of a rearwall 13 a, and a hub 132 at a center of the rear wall 13 a having athrough hole 131 for fastening members 15 a, such as bolts, for couplingthe rotor 13 to the shaft 4. An overall form of the rotor 13 ispreferably formed by press forming. There are a plurality of coolingfins 133 each formed to have a preset length in a radial directionaround the hub 132 of the rotor 13 for blowing air toward the stator 14during rotation of the rotor 13 for cooling heat generated at the stator14. The cooling fins 133 are formed by lancing, to bend the cooling fins133 at a right angle with respect to the rear wall 13 a toward theopening so as to form through holes 134 for ventilation. There is anembossing 135 between adjacent cooling fins 133 with a drain hole 136therein for draining water. There are fastening holes 137 for fasteninga connector 16 formed to the rotor 13 and positioning holes 138 forpositioning an assembly position of the connector 16 around the throughhole 131 in the hub 132 of the rotor 13 at fixed intervals. Theconnector 16 is serration coupled to an outer circumference of a rearend portion of the shaft 4 exposed at a rear of the rear bearing 6 b.The connector 16 is formed of resin having a vibration mode differentfrom the rotor 13 of steel or steel alloy plate, and also serves as abushing for the rotor 13. As shown in FIGS. 2B, 7 and 8, the connector16 has fastening holes 162 to correspond to the fastening holes 137 inthe hub 132 of the rotor 13, arranged in a circumferential direction ofa peripheral region thereof, and a dowel pin 160 between adjacentfastening holes 162 formed as a unit with the connector 16 for insertionin the positioning holes 138 in the rotor 13 for self alignment of thefastening holes 137 and 162 in the rotor 13 and the connector 16,respectively. The connector 16 has a serration 164 in an insidecircumference of the hub 163 matched to a serration on the rear end ofthe shaft 4, and reinforcing ribs 161 on outer circumference of the hub163 for reinforcing the hub 163. There is a hub 201 on the rear wall 200of the tub 2 having the bearing housing 7 inserted therein when the tubis injection molded, and fastening bosses 202 on an outer side of thehub 201 along a circumferential direction at fixed intervals forfastening the stator 14 to the rear wall 200 of the tub 2. There is asupporter 17 between the rear wall 200 of the tub 2 and the stator 14,of a form almost identical to an outline of the tub rear wall 200, fixedto the tub rear wall 200 when the stator 14 is assembled for supportingthe stator 14 and maintaining concentricity of the stator 14. Thesupporter 17 has a fore end brought into a close contact with an insideof ribs 203 at one side of the tub rear wall 200, and a rear end broughtinto a close contact with an outer circumference of a rear end of thebearing housing 7 which is not enclosed by the hub 132, but exposed. Inthe meantime, as shown in FIGS. 2B and 6, the stator 14 includes amagnetic core 145 of segregated layers of magnetic material, a frame 140of resin coated on the magnetic core 145, a coil 142 wound around eachof winding parts 141 on an outer circumference of the frame 140, andfastening ribs 143 on an inside of the frame 140 for fastening thestator 14 to the tub rear wall 200.

The operation of the driving unit in a drum type washing machine inaccordance with a first preferred embodiment of the present inventionwill be explained. The rotor 13 is rotated in response to a currentflowing to the coils 142 of the stator 14 in a sequence under thecontrol of a motor driving controller(not shown) fitted on a panel, andthe shaft 4, which is serration coupled with the connector 16 fixed tothe rotor 13 is rotated, together with the drum 3 as the power istransmitted to the drum 3 through the shaft 4.

The tub 2 of the drum type washing machine of the present invention,formed of a plastic with excellent heat resistance, is light and hasgood formability as the tub 2 is injection molded. Since the bearinghousing 7 in the drum type washing machine of the present invention isformed of a metal, such as aluminum and the like, the bearing housing 7is applicable to a drum type washing machine having a drying cycle, asthe bearing housing shows no thermal deformation. And, since themetallic bearing housing 7 of the present invention is formed integratedwith the tub 2 by inserting the bearing housing 7 in the hub 201 on thetub rear wall 200 before the tub 2 of plastic is injection molded, aseparate step for assembling the bearing housing 7 to the tub rear wall200 can be omitted, which simplifies an assembly process and reducesassembly man-hours. The “┐” form of the step 8 a in a front portion ofan inner circumference of the bearing housing 7 and the “└” form of thestep 8 b in a rear portion of an inner circumference of the bearinghousing 7 provide support to a rear end of the front bearing 6 a and afore end of the rear bearing 6 b mounted on outer circumference of theshaft 4 at both end portions thereof. That is, the steps 8 a and 8 b oninner circumferences of the metallic bearing housing 7 on both sidesthereof prevent both bearings 6 a and 6 b from being separated from thebearing housing 7. The positioning steps 400 a and 400 b on outercircumferences of the shaft 4 at front and rear portions thereof permiteasy positioning of the front bearing 6 a and the rear bearing 6 b onthe shaft 4 in the assembly. The front end portion of the shaft 4 iscoupled to the spider 10 in the rear wall, and the brass bushing 11press fit to the region from the exposed portion outside of the spider10 of the shaft 4 to the front bearing 6 a prevents rusting of the shaft4. The sealing member 12 outside of the bushing 11 prevents ingress ofwater toward the bearing.

In the meantime, the rotor 13 of the direct coupling type motor 5 ismounted on a center of the rear end portion of the shaft 4, with thestator 14 disposed on an inner side of the rotor 13, wherein the bendpart having the magnet setting surface 130 is formed along acircumferential direction of the sidewall 13 b, extending forward from aperiphery of the rear wall 13 a of the rotor 13, for supporting themagnets 13 c when the magnets 13 c are fitted to an inside surface ofthe rotor 13, to fabricate the rotor with ease. The through hole 131 ofthe hub 132 at a center of the rear wall 13 a of the rotor 13 permitsthe fastening member 15 b, such as a bolt or the like, to passtherethrough for fastening the rotor 13 to the shaft 4, and theplurality of cooling fins 133 arranged around the hub 132 of the rotor13 in a radial direction and having a certain length blow air toward thestator 14 during rotation of the rotor 13 for cooling down a heatgenerated at the stator 14. The cooling fins 133 are formed by lancing,so as to direct flow toward the opening of the rotor 13, and to leavethrough holes 134 for ventilation. The rotor 13 of steel or steel alloyplate is formed by pressing, which shortens a fabrication time periodand improves productivity. The embossing 135 between the adjacentcooling fins 133 of the rear wall 13 a of the rotor 13 improves anoverall strength of the rotor 13, and the drain hole 136 in theembossing 135 drains water.

In the meantime, the fastening holes 137 for fastening the connector andthe positioning holes 138 for fixing an assembly position of theconnector 16 around the through hole 131 in the hub 132 of the rotor 13permits an easy assembly of the connector 16 to the rotor. The connector16 is serration coupled to the outer circumference of the rear endportion of the shaft 4 exposed to rear of the rear bearing 6 b. That is,once the dowel pins 160 on the connector 16 are inserted in thepositioning holes 138 in the rotor 13, the fastening holes 137 and 162in the rotor 13 and the connector 16 are matched automatically, and byfastening the fastening members 15 c through the fastening holes 137 and162 in the rotor 13 and the connector 16, the connector 16 and the rotor13 can be assembled with ease. The connector 16 serves to damp vibrationfrom the rotor 13 to the shaft 4 as the connector 16, which is injectionmolded of a resin, has a different vibration mode from the rotor 13 ofsteel or steel alloy plate. The serration 164 in the inner circumferenceof the hub 163 of the connector 16 is fit to the serration 400 on therear end portion of the shaft 4, to transmit the rotating force of therotor 13 to the shaft, directly. The reinforcing ribs 161 on an outercircumference of the hub 163 of the connector 16 reinforce the hub 163.

In the meantime, the fastening bosses 202 along a circumference on anouter side of the hub 201 on the rear wall 200 of the tub 2 at fixedintervals allow the stator 14 to be fixed to the rear wall 200 of thetub 2 by using the fastening boss 202. The supporter 17 between the rearwall 200 of the tub 2 and the stator 14 having a form almost identicalto the outline of the rear wall 200 so as to be fixed to the rear wall200 of the tub 2 and have the stator 14 is fastened thereto permits thestator 14 to be supported and maintain concentricity. That is, once thesupporter 17 is fastened to the fastening bosses 204 on the tub rearwall 200, the fore end of the supporter 17 is brought into close contactwith an inside surface of the ribs 203 at one side of the tub rear wall200 and the rear end of the supporter 17 is brought into close contactwith the outer circumference of the rear end portion of the bearinghousing 7 at a central portion of the tub rear wall 200, which can notbe enclosed, but exposed, by the hub 132, such that the supporter 17supports the stator 14 as well as maintains a concentricity of thestator 14.

The structure of a driving unit in a drum type washing machine inaccordance with a first preferred embodiment of the present inventionhas the following advantages.

The motor direct coupling structure of the drum type washing machine inaccordance with a first preferred embodiment of the present inventionprovides for reduced repair, and reduced power loss.

The bearing housing of metal in the drum type washing machine inaccordance with a first preferred embodiment of the present inventionshows no thermal deformation, allowing this to be applied to a producthaving a drying function.

The rotor of steel or steel alloy plate formed by pressing in the drumtype washing machine in accordance with a first preferred embodiment ofthe present invention requires a very short fabrication time period,with improved productivity, because the steel or steel alloy platepressing has excellent formability.

And, the magnet setting surface on the rotor of the present inventionimproves a workability in fitting the magnets, and the drain holes, thecooling fins, and the through holes provided to the rotor can preventoverheating of the motor, improve a reliability of the motor, andprolong a lifetime of the motor.

And, the connector having a vibration mode different from the rotor inthe drum type washing machine of the present invention can attenuate thevibration transmitted from the rotor to the shaft, and the supporter cansupport the stator and maintain a concentricity of the stator.

A driving unit in a drum type washing machine in accordance with asecond preferred embodiment of the present invention will be explainedwith reference to FIGS. 3˜9, in detail. FIG. 9 illustrates alongitudinal section of a driving unit in a drum type washing machine inaccordance with a second preferred embodiment of the present invention.The rotor, the stator and the connector in the second preferredembodiment of the present invention are identical to those of the firstembodiment, to which the same names and reference symbols are given, andwill be explained with reference to FIGS. 3˜8.

The drum type washing machine in accordance with a second preferredembodiment of the present invention includes a tub 2 mounted inside of acabinet 1, a drum 3 mounted inside of the tub 2, a shaft 4 connected tothe drum mounted inside of the tub 3 for transmission of a driving forcefrom the motor 5 to the drum, a front bearing 6 a and a rear bearing 6 bmounted on outer circumferences of the shaft 4 at both end portionsthereof respectively, a bearing housing 7 built in a central portion ofthe rear wall 200 of the tub 3 for supporting the front bearing 6 a, arotor 13 coupled to the shaft 4, a stator 14 provided inward of therotor 13 coupled to the tub rear wall 200, a connector 16 that isserration coupled to an outer circumference of the shaft 4 in front ofthe rear bearing 6 b and fixed to the rotor 13 for transmission of arotating force of the rotor 13 to the shaft 4, a supporter 17 fittedbetween the rear wall 200 of the tub 2 and the stator 14 for supportingthe stator 14 and maintaining a concentricity when the stator 14 ismounted to the tub rear wall 200, and a bearing bracket 9 fixed to thetub rear wall 200 for covering an outside of the rotor 13 and supportingthe front end portion of the rear bearing 6 b. The tub 2 is formed ofplastic, and has an opened front and a closed rear wall 200 having athickness that is greater than a thickness of a sidewall, and thebearing housing 7 at the central portion of the rear wall 200 of the tub2 is formed of a metal, wherein the bearing housing 7 is insertinjection molded when the plastic tub 2 is injection molded, such thatthe bearing housing 7 is integrated with the tub rear wall 200. Thebearing housing 7 is preferably formed of an aluminum alloy.

In the meantime, there is a step 7 a on an inner circumference of themetallic bearing housing 7 for supporting the front bearing 6 a toprevent the front bearing 7 from being separated from the bearinghousing 7. The step 7 a on the inner circumference of the bearinghousing 7 has a form of “┐” to support a rear end portion of the frontbearing 6 a mounted on a front end portion of the shaft 4. The front endportion of the shaft 4 is fixed to a spider 10 in the rear wall 200 ofthe drum 3, a region of the shaft 4 from a portion exposed at a rear ofthe spider 10 to the front bearing 6 a has a bushing 11 of brass pressfit thereon for prevention of rusting, and there is a sealing member 12on an outer surface of the bushing 11 for preventing ingress of watertoward the front bearing 6 a. The connector 16 is serration coupled tothe rear end portion of the shaft 4 for connection between the rotor 13of the direct coupling type motor 5 and the shaft 4, the rotor 13 isfixed to the connector 16 with fastening members 15 c, and the stator14, forming the direct coupling type motor together with the rotor 13,is fixed to the rear wall 200 of the tub 2 inward of the rotor 13. Asshown in FIGS. 3˜5, the rotor 13 of steel or steel alloy plate includesa bend part having a magnet setting surface 130 formed along acircumferential direction of a sidewall 13 b extended forward from aperiphery of the rear wall 13 a of the rotor 13, for supporting magnets13 c fitted to a front portion of an inside surface of the rotor 13, anda hub 132 having a through hole 131 at a center of the rear wall 13 a ofthe rotor 13 so that a fastening member 15 a, such as a bolt or thelike, can pass through for coupling the rotor 13 to the shaft 4. Anoverall form of the rotor 13 is preferably formed by pressing. There area plurality of cooling fins 133 each formed to have a preset length in aradial direction around the hub 132 of the rotor 13 for blowing airtoward the stator 14 during rotation of the rotor 13 for cooling heatgenerated at the stator 14. The cooling fins 133 are formed by lancing,to bend the cooling fins 133 at a right angle with respect to the rearwall 13 a oriented toward the opening to leave through holes 134 forventilation. There is an embossing 135 between adjacent cooling fins 133with a drain hole 136 therein for draining water. There are fasteningholes 137 for fastening a connector 16 to the rotor 13 and positioningholes 138 for positioning an assembly position of the connector 16around the through hole 131 in the hub 132 of the rotor 13 at fixedintervals. The connector 16 is serration coupled to an outercircumference of a rear end portion of the shaft 4 exposed at a rear ofthe rear bearing 6 b. The connector 16 is formed of resin having avibration mode different from the rotor 13 of steel or steel alloyplate. As shown in FIGS. 7˜9, the connector 16 has fastening holes 162to correspond to the fastening holes 137 in the hub 132 of the rotor 13arranged in a circumferential direction of a peripheral region thereofand a dowel pin 160 between adjacent fastening holes 162 formed as aunit with the connector 16 for insertion in the positioning hole 138 inthe rotor 13 for self alignment of the fastening holes 137 and 162 inthe rotor 13 and the connector 16, respectively. The connector 16 has aserration 164 in an inside circumference of the hub 163 matched to theserration on the rear end of the shaft 4, and reinforcing ribs 161 on anouter circumference of the hub 163 for reinforcing the hub 163. There isa hub 201 on the rear wall 200 of the tub 2 having the bearing housing 7inserted therein when the tub 2 is injection molded, and fasteningbosses 202 on an outer side of the hub 201 along a circumferentialdirection at fixed intervals for fastening the stator 14 to the rearwall 200 of the tub 2. There is a supporter 17 between the rear wall 200of the tub 2 and the stator 14, having a form almost identical to anoutline of the rear wall 200, fixed to the tub 2 rear wall 200 when thestator 14 is assembled for supporting the stator 14 and maintainingconcentricity of the stator 14. Once the supporter 17 is fastened to thesupport fastening bosses 204, a fore end of the supporter 17 is broughtinto close contact with an inside of ribs 203 at one side of the tubrear wall 200, and a rear end thereof is brought into close contact withan outer circumference of a rear end of the bearing housing 7 which isnot enclosed by the hub 132, but exposed. Thus, the supporter 17supports the stator 14 and maintains a concentricity of the stator 14.In the meantime, as shown in FIGS. 3 and 6, the stator 14 includes aring formed frame 140, a coil 142 wound around each of winding parts 141on an outer circumference of the frame 140, and fastening ribs 143 on aninside of the frame 140 for fastening the stator 14 to the tub rear wall200.

In the meantime, referring to FIG. 9, there is an “└” formed step 9 b atan inner end portion of the bearing bracket 9 fixed to the tub rear wall200 to cover an outer side of the rotor 13. And, there is a rear bearingfixing member 15 b at a rear end of the shaft 4 for supporting a rearsurface of the shaft 4 to prevent the rear bearing from being separatedfrom the shaft 4.

The operation of the driving unit in a drum type washing machine inaccordance with a second preferred embodiment of the present inventionwill be explained. The rotor 13 is rotated in response to a currentflowing to the coils 142 of the stator 14 in a sequence under thecontrol of a motor driving controller(not shown) fitted on a panel, andthe shaft 4, which is serration coupled with the connector 16 fixed tothe rotor 13, is rotated, together with the drum 3 as power istransmitted to the drum 3 through the shaft 4.

The drum type washing machine in accordance with the second preferredembodiment of the present invention has advantages. Like the firstembodiment of the present invention, since the tub 2 is formed of aplastic with excellent heat resistance, the tub 2 is light and has goodformability as the tub 2 is injection molded. Since the bearing housing7 is formed of a metal, such as an aluminum alloy and the like, thebearing housing 7 is applicable to a drum type washing machine alsohaving a drying cycle as the bearing housing 7 shows no thermaldeformation. And, since the metallic bearing housing 7 is formedintegrated with the tub 2 by inserting the bearing housing 7 in the hub201 on the tub rear wall 200 before the tub 2 of plastic is injectionmolded, a separate step for assembling the bearing housing 7 to the tubrear wall 200 can be omitted, which simplifies an assembly process andreduces assembly man-hours. The step 7 a in an inner circumference of afront portion of the bearing housing 7 in the second embodiment of thepresent invention supports a rear end of the front bearing 6 a mountedon an outer circumference of the fore end portion of the shaft 4. Thatis, the “┐” formed step 7 a in a front portion of an inner circumferenceof the metallic bearing housing 7 of the present invention providessupport to the front bearing 6 a without being separated from thebearing housing 7. And, the “└” formed step 9 b in an end portion of aninner circumference of the metallic bearing bracket 9 covering an outerside of the rotor 13 fixed to the tub rear wall 200 provides support toa front end of the rear bearing 6 b mounted on the rear end portion ofthe shaft 4, and the rear bearing fixing member 15 b on the rear endsurface of the shaft 4 prevents the rear bearing 6 b from beingseparated from the shaft 4.

In the meantime, in the second preferred embodiment of the presentinvention, since the front bearing 6 a is mounted in the bearing housing7 having been insert injection molded in the tub 2, and the rear bearing6 b is mounted in an inside of a center portion of the bearing bracket9, a distance between the front and rear bearings 6 a and 6 b on theshaft 4 becomes greater, between which the rotor 13 is mounted. Thegreater distance between the front and rear bearings 6 a and 6 b betterwithstands a load caused by imbalance of laundry in the drum 3 duringspinning, and a supporting force to the rotor 13 is enhanced as therotor 13 of the motor is mounted between the front and rear bearings 6 aand 6 b. Like the first preferred embodiment of the present invention,in the second preferred embodiment of the present invention, the brassbushing 11 press fit to the region from the exposed portion outside ofthe spider 10 of the shaft 4 to the front bearing 6 a prevents rustingof the shaft 4. Similarly, the sealing member 12 outside of the bushing11 prevents ingress of water toward the bearing.

Like the first preferred embodiment, as shown in FIGS. 3 to 6, the bendpart having the magnet setting surface 130 is formed along acircumferential direction of the sidewall 13 b extended forward from aperiphery of the rear wall 13 a of the rotor 13, for supporting themagnets 13 c when the magnets 13 c are fitted to an inside surface ofthe rotor 13, to fabricate the rotor with ease. Like the first preferredembodiment of the present invention, in the second preferred embodimentof the present invention, the plurality of cooling fins 133 around thehub 132 of the rotor 13 in a radial direction having a certain lengthblow air toward the stator 14 during rotation of the rotor 13 forcooling down heat generated at the stator 14. The cooling fins 133 areformed by lancing, oriented toward the opening of the rotor 13, andleave through holes 134 for ventilation. Since the rotor 13 is formed ofsteel or steel alloy plate by pressing, which shortens a fabricationtime period significantly, productivity is improved. The embossing 135between the adjacent cooling fins 133 of the rear wall 13 a of the rotor13 improves an overall strength of the rotor 13, and the drain hole 136in the embossing 135 drains water.

In the meantime, the fastening holes 137 for fastening the connector andthe positioning holes 138 for fixing an assembly position of theconnector 16 around the through hole 131 in the hub 132 of the rotor 13permits an easy assembly of the connector 16 to the rotor 13. Theconnector 16 is serration coupled to the outer circumference of the rearend portion of the shaft 4. That is, once the dowel pins 160 on theconnector 16 are inserted in the positioning holes 138 in the rotor 13,the fastening holes 137 and 162 in the rotor 13 and the connector 16 arematched automatically, and by fastening the fastening members 15 cthrough the fastening holes 137 and 162, the connector 16 and the rotor13 can be assembled with ease. The connector 16 serves to damp vibrationfrom the rotor 13 to the shaft 4 as the connector 16 injection molded ofa resin has a different vibration mode from the rotor 13 of steel orsteel alloy plate. The serration 164 in the inner circumference of thehub 163 of the connector 16 is fit to the serration 400 on the rear endportion of the shaft 4, to transmit the rotating force of the rotor 13to the shaft, directly. The reinforcing ribs 161 on an outercircumference of the hub 163 of the connector 16 reinforce the hub 163.

In the meantime, the fastening bosses 202 along a circumference on anouter side of the hub 201 on the rear wall 200 of the tub 2 at fixedintervals permit the stator 14 to be fixed to the rear wall 200 of thetub 2 by using the fastening boss 202. The supporter 17 between the rearwall 200 of the tub 2 and the stator 14 having a form almost identicalto the outline of the rear wall 200 for being fixed to the rear wall 200of the tub 2 when the stator 14 is fastened permits the stator 14 to besupported and concentricity to be maintained. That is, the front end ofthe supporter 17 is brought into close contact with an inside surface ofthe ribs 203 at one side of the tub rear wall 200 and the rear end ofthe supporter 17 is brought into close contact with the outercircumference of the rear end portion of the bearing housing 7 at acentral portion of the tub rear wall 200, which can not be enclosed, butexposed, by the hub 132, such that the supporter 17 supports the stator14 as well as maintains a concentricity of the stator 14.

The structure of a driving unit in a drum type washing machine inaccordance with a second preferred embodiment of the present inventionhas the following advantages.

The motor direct coupling structure of the drum type washing machine ofthe present invention provides reduced repair, noise and power loss.

The bearing housing of metal in the drum type washing machine of thepresent invention shows no thermal deformation, and may be applied to aproduct having a drying function.

The rotor of steel or steel alloy plate formed by pressing in the drumtype washing machine of the present invention requires a very shortfabrication time period, with improved productivity, because the steelor steel alloy plate pressing has excellent formability.

And, the magnet setting surface on the rotor of the present inventionimproves a workability in fitting the magnets, and the drain holes, thecooling fins, and the through holes provided to the rotor can preventoverheating of the motor, improve a reliability of the motor, andprolong a lifetime of the motor.

And, the connector having a vibration mode different from the rotor inthe drum type washing machine of the present invention can attenuate thevibration transmitted from the rotor to the shaft, and the supporter cansupport the stator and maintain a concentricity of the stator.

Particularly, in the second preferred embodiment of the presentinvention, the greater distance between the front and rear bearingspermits better withstands a load caused by imbalance of laundry in thedrum 3 during spinning, and a supporting capability to the rotor isenhanced as the rotor of the motor is mounted between the front and rearbearings.

Thus, by improving a structure of a driving unit of a drum type washingmachine, the present invention can reduce noise, repair and power loss,can improve a washing capability, can improve a product reliability,and, by improving workability in fabrication of components of thedriving unit, can improve a productivity.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the structure of a drivingunit in a drum type washing machine of the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A washing machine comprising: a tub comprising plastic and includingan opened front, a closed rear wall, and a sidewall extending from aperiphery of the rear wall to the opened front, wherein the tub iscylindrical; a drum mounted rotatably in the tub; a bearing housingcomprising metal, and including a cylindrical aperture therethroughdefining an inner circumference, wherein the bearing housing is mountedproximate to a central portion of the rear wall of the tub by insertinjection molding, and protrudes toward the stator; a shaft passingthrough the bearing housing, the shaft having one end directly connectedto the drum; at least one bearing mounted between the shaft and thebearing housing for supporting the shaft; a stator including a magneticcore having a stack of layers of magnetic material and a winding parthaving a coil wound thereon for forming a magnetic force; and a rotorcomprising a sidewall, a rear wall and a permanent magnet fixed to thesidewall of the rotor, wherein the rotor is coupled to the shaft.
 2. Thewashing machine of claim 1, wherein a body of the rotor is entirelyformed of metal.
 3. The washing machine of claim 1, wherein the rearwall and the side wall of the rotor are entirely formed of metal.
 4. Thewashing machine of claim 1, further comprising a connector connectingthe rotor to the rotor.
 5. The washing machine of claim 4, wherein theconnector is serration coupled to the shaft.
 6. The washing machine ofclaim 4, wherein the connector has a flange abutting the rotor.
 7. Thewashing machine of claim 4, wherein the connector is formed of anelectrically insulating material.
 8. The washing machine of claim 1,further comprising a supporter inserted between the stator and the rearwall of the tub.
 9. The washing machine of claim 8, wherein thesupporter is formed separately from the stator and the rear wall of thetub.
 10. The washing machine of claim 8, wherein the supporter surroundsthe bearing housing.
 11. The washing machine of claim 8, wherein thesupporter contacts the bearing housing.
 12. The washing machine of claim1, wherein the supporter abuts the protruding bearing housing.
 13. Thewashing machine of claim 1, wherein the bearing housing protrudes towardstator from the rear wall of the tub.
 14. The washing machine of claim1, wherein the bearing housing rises above portions of the rear wall ofthe tub other than the central portion thereof.
 15. The washing machineof claim 1, wherein at least a portion of the protruding bearing housingis exposed outside the rear wall of the tub.
 16. The washing machine ofclaim 1, wherein the protruding bearing housing includes an end facingthe rotor, and wherein the end of the protruding bearing housing isexposed outside the rear wall of the tub.
 17. The washing machine ofclaim 1, wherein an outer circumference of the protruding bearing isexposed outside the rear wall of the tub.
 18. The washing machine ofclaim 1, wherein the bearing housing is inserted into the stator. 19.The washing machine of claim 1, wherein the bearing housing faces aninner circumference of the stator.
 20. The washing machine of claim 1,wherein the bearing housing directly faces an inner circumference of thestator
 21. The washing machine of claim 1, wherein the bearing housingdirectly faces an inner surface of the rotor.
 22. The washing machine ofclaim 1, wherein the protruding bearing housing receives the bearing.23. The washing machine of claim 1, wherein the stator is disposedaround the bearing housing.
 24. The washing machine of claim 1, whereinthe stator encloses the bearing housing.
 25. The washing machine ofclaim 1, wherein an inner circumference of the stator faces the bearinghousing.